Analysis Of Burst Pressure And Simulation Of Progressive Damage For Large Capacity Steel Liner Composite Cylinder

Large capacity steel liner composite cylinder had advantages of light weight,high strength and so on compared with traditional steel cylinder.Since composite cylinder entered into Chinese market in 2011,it developed rapidly and had a very broad market prospect.However,in process of manufacturing,transportation and using,it was inevitable that defects would occur on the outer surface of composite winding layer due to collision,friction,etc.These defects would affect the safe operation of cylinder.Based on above situation,burst pressure and progressive damage of large capacity steel liner composite cylinders were studied by finite element software ANSYS Workbench.The finite element software was used to construct a large capacity hoop-wrapped composite cylinder model,and three volume defects were established on surface of winding layer.The process of numerical model and defect establishment were described in detail.Stress distribution and size of cylinder liner and winding layer with different winding layer surface defects were analyzed under the design burst pressure(50MPa).Simulation results showed that the liner and winding layer would have stress concentration at the defect position,and after exceeding the defect range,the stress would rapidly decrease and remain stable;defects of winding layer had little effect on liner stress,but stress of winding layer would increase sharply.The burst pressure of the cylinder without defects and with different winding layer defects were predicted respectively by the maximum strain criterion and the maximum stress criterion.Simulation results showed that the burst pressure of the cylinder with winding layer defects were significantly reduced and the depth of defect had more influence than the defect area.The predicted burst pressure of the non-defective cylinder was 58.5MPa.The data obtained from the hydraulic burst testing of the cylinder was 56.0 MPa,there was a difference of 4.46% between 56.0MPa and 58.5MPa.The accuracy of the finite element simulation was verified by comparing the simulation results with the experimental data.Base on above discussion,critical size of winding layer that had no effect on burst pressure was studied by maximum stress criterion which was more accurate.Simulation results show that burst pressure would obviously decrease and depth had a greater influence on it;for cylinder discussed in this paper,conclusion about critical size had no influence was that area was 200mm×200mm and depth was 1mm.As microscopic damage of cylinder was gradually accumulated in use,it would cause macroscopic level damage like stiffness degradation.In this paper,the progressive damage process of large capacity steel liner composite cylinder was simulated based on the Puck criterion.The simulation results show that the failure order of the winding layer was matrix tensile failure ? matrix compression failure/ matrix shear failure ?delamination failure ?fiber fracture failure;Except that matrix tensile failure was developed from the outside to the inside,other failure modes were developed from the inside to the outside;the hoop-wrapped winding layer failed before the spiral winding layer;failure modes were not affected by autofrettage of cylinder except matrix tensile failure.By analysis of progressive damage process of composite cylinder,it was predicted that the cylinder burst pressure was 58.8MPa,and the accuracy of the finite element simulation was verified by literature.